[support.types]

The contents and meaning of the header

17.2.2 Header <cstdlib> synopsis [cstdlib.syn]

namespace std { using size_t = see below; / freestanding using div_t = see below; / freestanding using ldiv_t = see below; / freestanding using lldiv_t = see below; / freestanding } #define NULL see below / freestanding #define EXIT_FAILURE see below / freestanding #define EXIT_SUCCESS see below / freestanding #define RAND_MAX see below #define MB_CUR_MAX see below namespace std { / Exposition-only function type aliases extern "C" using c-atexit-handler = void(); / exposition only extern "C++" using atexit-handler = void(); / exposition only extern "C" using c-compare-pred = int(const void*, const void*); / exposition only extern "C++" using compare-pred = int(const void*, const void*); / exposition only / [support.start.term], start and termination [[noreturn]] void abort() noexcept; / freestanding int atexit(c-atexit-handler* func) noexcept; / freestanding int atexit(atexit-handler* func) noexcept; / freestanding int at_quick_exit(c-atexit-handler* func) noexcept; / freestanding int at_quick_exit(atexit-handler* func) noexcept; / freestanding [[noreturn]] void exit(int status); / freestanding [[noreturn]] void _Exit(int status) noexcept; / freestanding [[noreturn]] void quick_exit(int status) noexcept; / freestanding char* getenv(const char* name); int system(const char* string); / [c.malloc], C library memory allocation void* aligned_alloc(size_t alignment, size_t size); void* calloc(size_t nmemb, size_t size); void free(void* ptr); void free_sized(void* ptr, size_t size); void free_aligned_sized(void* ptr, size_t alignment, size_t size); void* malloc(size_t size); void* realloc(void* ptr, size_t size); size_t memalignment(const void* p); / freestanding double atof(const char* nptr); int atoi(const char* nptr); long int atol(const char* nptr); long long int atoll(const char* nptr); double strtod(const char* nptr, char* endptr); int strfromd(char* s, size_t n, const char* format, double fp); int strfromf(char* s, size_t n, const char* format, float fp); int strfroml(char* s, size_t n, const char* format, long double fp); float strtof(const char* nptr, char* endptr); long double strtold(const char* nptr, char* endptr); long int strtol(const char* nptr, char* endptr, int base); long long int strtoll(const char* nptr, char* endptr, int base); unsigned long int strtoul(const char* nptr, char* endptr, int base); unsigned long int strtoull(const char* nptr, char* endptr, int base); / [c.mb.wcs], multibyte / wide string and character conversion functions int mblen(const char* s, size_t n); int mbtowc(wchar_t* pwc, const char* s, size_t n); int wctomb(char* s, wchar_t wchar); size_t mbstowcs(wchar_t* pwcs, const char* s, size_t n); size_t wcstombs(char* s, const wchar_t* pwcs, size_t n); / [alg.c.library], C standard library algorithms void* bsearch(const void* key, void* base, size_t nmemb, size_t size, / freestanding c-compare-pred* compar); void* bsearch(const void* key, void* base, size_t nmemb, size_t size, / freestanding compare-pred* compar); const void* bsearch(const void* key, const void* base, size_t nmemb, / freestanding size_t size, c-compare-pred* compar); const void* bsearch(const void* key, const void* base, size_t nmemb, / freestanding size_t size, compare-pred* compar); void qsort(void* base, size_t nmemb, size_t size, c-compare-pred* compar); / freestanding void qsort(void* base, size_t nmemb, size_t size, compare-pred* compar); / freestanding / [c.math.rand], low-quality random number generation int rand(); void srand(unsigned int seed); / [c.math.abs], absolute values constexpr int abs(int j); / freestanding constexpr long int abs(long int j); / freestanding constexpr long int abs(long long int j); / freestanding constexpr floating-point-type abs(floating-point-type j); / freestanding-deleted constexpr long int labs(long int j); / freestanding constexpr long int llabs(long long int j); / freestanding constexpr div_t div(int numer, int denom); / freestanding constexpr ldiv_t div(long int numer, long int denom); / freestanding; see [library.c] constexpr lldiv_t div(long long int numer, long long int denom); / freestanding; see [library.c] constexpr ldiv_t ldiv(long int numer, long int denom); / freestanding constexpr lldiv_t lldiv(long long int numer, long long int denom); / freestanding }

The contents and meaning of the header <cstdlib> are the same as the C standard library header <stdlib.h>, except that it does not declare the types wchar_t or once_flag, and does not declare the function call_once, and except as noted in [support.types.nullptr], [support.types.layout], [support.start.term], [c.malloc], [c.mb.wcs], [alg.c.library], [c.math.rand], and [c.math.abs].

[Note 1:

Several functions have additional overloads in this document, but they have the same behavior as in the C standard library .

— end note]

17.2.3 Null pointers [support.types.nullptr]

The type nullptr_t is a synonym for the type of a nullptr expression, and it has the characteristics described in [basic.fundamental] and [conv.ptr].

[Note 1:

Although nullptr's address cannot be taken, the address of another nullptr_t object that is an lvalue can be taken.

— end note]

The macro NULL is an implementation-defined null pointer constant.151

17.2.4 Sizes, alignments, and offsets [support.types.layout]

The macro offsetof(type, member-designator) has the same semantics as the corresponding macro in the C standard library header <stddef.h>, but accepts a restricted set of type arguments in this document.

Use of the offsetof macro with a type other than a standard-layout class ([class.prop]) is conditionally-supported.152

The expression offsetof(type, member-designator) is never type-dependent and it is value-dependent if and only if type is dependent.

The result of applying the offsetof macro to a static data member or a function member is undefined.

No operation invoked by the offsetof macro shall throw an exception and noexcept(offsetof(type, member-designator)) shall be true.

The type ptrdiff_t is an implementation-defined signed integer type that can hold the difference of two subscripts in an array object, as described in [expr.add].

The type size_t is an implementation-defined unsigned integer type that is large enough to contain the size in bytes of any object ([expr.sizeof]).

Recommended practice: An implementation should choose types for ptrdiff_t and size_t whose integer conversion ranks ([conv.rank]) are no greater than that of signed long int unless a larger size is necessary to contain all the possible values.

The type max_align_t is a trivially copyable standard-layout type whose alignment requirement is at least as great as that of every scalar type, and whose alignment requirement is supported in every context ([basic.align]).

std::is_trivially_default_constructible_v<max_align_t> is true.

17.2.5 byte type operations [support.types.byteops]

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template<class IntType>
  constexpr byte& operator<=(byte& b, IntType shift) noexcept;

Effects: Equivalent to: return b = b << shift;

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template<class IntType>
  constexpr byte operator<(byte b, IntType shift) noexcept;

Effects: Equivalent to: return static_cast<byte>(static_cast<unsigned int>(b) << shift);

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template<class IntType>
  constexpr byte& operator>=(byte& b, IntType shift) noexcept;

Effects: Equivalent to: return b = b >> shift;

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template<class IntType>
  constexpr byte operator>(byte b, IntType shift) noexcept;

Effects: Equivalent to: return static_cast<byte>(static_cast<unsigned int>(b) >> shift);

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constexpr byte& operator|=(byte& l, byte r) noexcept;

Effects: Equivalent to: return l = l | r;

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constexpr byte operator|(byte l, byte r) noexcept;

Effects: Equivalent to: return static_cast<byte>(static_cast<unsigned int>(l) | static_cast<unsigned int>(r));

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constexpr byte& operator&=(byte& l, byte r) noexcept;

Effects: Equivalent to: return l = l & r;

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constexpr byte operator&(byte l, byte r) noexcept;

Effects: Equivalent to: return static_cast<byte>(static_cast<unsigned int>(l) & static_cast<unsigned int>(r));

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constexpr byte& operator^=(byte& l, byte r) noexcept;

Effects: Equivalent to: return l = l ^ r;

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constexpr byte operator^(byte l, byte r) noexcept;

Effects: Equivalent to: return static_cast<byte>(static_cast<unsigned int>(l) ^ static_cast<unsigned int>(r));

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constexpr byte operator~(byte b) noexcept;

Effects: Equivalent to: return static_cast<byte>(~static_cast<unsigned int>(b));

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template<class IntType>
  constexpr IntType to_integer(byte b) noexcept;

Effects: Equivalent to: return static_cast<IntType>(b);

17 Language support library [support]

17.2 Common definitions [support.types]

17.2.1 Header <cstddef> synopsis [cstddef.syn]

17.2.2 Header <cstdlib> synopsis [cstdlib.syn]

17.2.3 Null pointers [support.types.nullptr]

17.2.4 Sizes, alignments, and offsets [support.types.layout]

17.2.5 byte type operations [support.types.byteops]

17.2.1 Header <cstddef> synopsis [cstddef.syn]

17.2.2 Header <cstdlib> synopsis [cstdlib.syn]

17.2.3 Null pointers [support.types.nullptr]

17.2.4 Sizes, alignments, and offsets [support.types.layout]

17.2.5 byte type operations [support.types.byteops]